Automated material distribution control for stretch blow molded articles

A method for inspecting the material distribution of a sequence of blow molded containers in a continuous production process, the method comprising:

• providing injection molded axially extending parisons, each parison having at least one indicator of material distribution at a predetermined position along the axial extent of the parison;
• thermally conditioning the parisons in the continuous production process to a temperature profile suitable for blow molding;
• blow molding the heated parisons so that each material distribution indicator is transformed to a corresponding axial location along the blow molded container;
• detecting, from at least some of the blow molded containers in the production process, the axial location of the indicator relative to a control location;
• determining for the at least some blow molded containers a material distribution outcome based on the detected axial locations of each indicator;
• selecting a sample of containers from the sequence of stretch blow molded containers;
• calculating an average material distribution outcome for the sample based on the determined material distribution outcome for each blow molded container in the sample;
• comparing the average material distribution outcome to a standard material distribution representing a nominal blow molded container to obtain an average material distribution variance;
• and
• providing a signal based on the comparison.

A method for controlling the material distribution of a sequence of stretch blow molded containers in a continuous production process, the method comprising:

• providing injection molded axially extending parisons, each parison having at least one indicator of material distribution at a predetermined position along the axial extent of each parison;
• heating the parisons in the continuous production sequence by exposure to a plurality of separate heating zones disposed along the axial extent of the parisons;
• stretch blow molding the heated parisons so that the material distribution indicator is transformed to a corresponding position along the axial extent of the blow molded container;
• detecting for each blow molded container an axial location relative to a control location for each indicator of material distribution for each blow molded container;
• determining for each blow molded container a respective material distribution outcome based on the detected axial location of each indicator;
• selecting a sample from the sequence of stretch blow molded containers;
• calculating an average material distribution outcome for the sample based on the determined material distribution outcome for each blow molded container in the sample;
• comparing the average material distribution outcome to a standard material distribution outcome for a nominal container to obtain an average material distribution variance;
• comparing the average material distribution variance to a set of predetermined variance case options;
• selecting one variance case option based on the comparison;
• and
• implementing a process adjustment related to the selected variance case option.

A control system for controlling the material distribution for a sequence of stretch blow molded containers in a continuous production process, the system comprising:

• a parison supply section supplying a plurality of injection molded, axially extending parisons, each parison having at least one indicator of material distribution at a predetermined position along the axial extent of the parison;
• a parison thermal conditioning section having a plurality of separate axially differentiated conditioning zones to vary the temperature along the axial extent of the parisons;
• a blow molding section transforming the thermally conditioned parisons into axially extended, blow molded containers having at least one indicator of material distribution at corresponding positions;
• an optical detector sensing the axial location of at least one indicator of material distribution on each blow molded container;
• a computer having an input coupled to the optical detector, the computer determining a material distribution outcome for each blow molded container, accumulating data representative of the material distribution outcome for a group of containers, computing an average material distribution characteristic for the group of containers, classifying the average material distribution characteristic in one of a pre-defined set of classes, and providing a signal to an output of the computer based on the selected classification;
• and
• a control feedback circuit coupled to the output of the computer and to one of the parison supply section, the parison thermal conditioning section and the blow molding section implementing at least one predetermined process adjustment designed to modify the material distribution of subsequent blow molded containers.

A control system for controlling the material distribution for a sequence of stretch blow molded containers in a continuous production process, the system comprising:

• a parison supply section supplying a plurality of injection molded, axially extending parisons, each parison having at least one indicator of material distribution at a predetermined position along the axial extent of the parison;
• a parison thermal conditioning section having a plurality of separate axially differentiated conditioning zones to vary the temperature along the axial extent of the parisons;
• a blow molding section transforming the thermally conditioned parisons into axially extended, blow molded containers having at least one indicator of material distribution at corresponding positions;
• an optical detector sensing the axial location of at least one indicator of material distribution on each blow molded container;
• a computer having an input coupled to the optical detector, the computer determining a material distribution outcome for each blow molded container, comparing the material distribution outcomes to a plurality of preset material distribution variance characterizations, and implementing a decision sequence to select one of the preset characterizations to generate an output signal to an output of the computer;
• and
• a control feedback circuit coupled to the output of the computer and to one of the parison supply section, the parison thermal conditioning section and the blow molding section implementing for certain of the preset material distribution variance characterizations at least one predetermined process adjustment designed to modify the material distribution of subsequent blow molded containers.

A method for controlling the material distribution of a sequence of stretch blow molded plastic containers in a continuous manufacturing process, the method comprising the steps of:

• providing a continuous production sequence of injection molded parisons;
• heating the parisons in the continuous production sequence by exposure to a plurality of axially distributed heating zones;
• stretch blow molding the heated parisons into containers, the containers being output from the blow molding operation as a sequence;
• identifying a characteristic of material distribution for each blow molded container in the sequence;
• comparing the identified material distribution characteristic of each container to a standard material distribution characteristic for a nominal container to detect a material distribution variance;
• selecting one of a predetermined set of variance case options based on the detected material distribution variance;
• and
• implementing a process adjustment related to the selected variance case option to modify a processing variable of the manufacturing process.

A method for controlling the material distribution of a sequence of stretch blow molded plastic containers in a continuous manufacturing process, the method comprising the steps of:

• providing a continuous production sequence of injection molded parisons;
• heating the parisons in the continuous production sequence by exposure to a plurality of axially distributed heating zones;
• stretch blow molding the heated parisons into containers, the containers being output from the blow molding operation as a sequence;
• selecting a sample from the sequence of stretch blow molded containers;
• and
• calculating an average material distribution for the sample based on the detected material distribution for each blow molded container in the sample;
• comparing the identified material distribution characteristic of each container to a standard material distribution characteristic for a nominal container to detect a material distribution variance;
• selecting one of a predetermined set of variance case options based on the detected material distribution variance;
• and
• implementing a process adjustment related to the selected variance case option to modify a processing variable of the manufacturing process.

A control system for controlling the material distribution for a sequence of stretch blow molded containers in a continuous production process, the system comprising:

• a parison supply section supplying a plurality of injection molded parisons;
• a parison thermal conditioning section having a plurality of axially differentiated conditioning zones to thermally condition the parisons;
• a blow molding section transforming the thermally conditioned parisons into blow molded containers;
• an optical detector sensing at least one indicator of material distribution on each blow molded container;
• a computer having an input coupled to the optical detector, the computer determining a material distribution characteristic for each blow molded container based on the input from the optical detector;
• a plurality of preset material distribution variance characterizations, and
• a decision sequence to select one of the preset characterizations to generate an output signal;
• and
• a control feedback circuit coupled to receive the output signal and coupled to one of:
• the parison supply section, the parison thermal conditioning section and the blow molding section, the control feedback circuit implementing for certain material distribution characteristics at least one predetermined process adjustment designed to modify the material distribution of subsequent blow molded containers.